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Aureobasidiumcomprises dimorphic yeast-like fungi that usually produce melanised cells at maturity. Species are globally distributed and ubiquitous, colonizing a variety of habitats. At present, ca 40 species are accepted, with the type,A. pullulans, representing a complex of unresolved cryptic species. In this study, we isolated 128Aureobasidiumfrom multiple temperate and tropical regions. We performed multigene analyses using eight loci (ITS, 28S,EF1a,ELO2,RPB2,BTUB, mtLSU and mtSSU) on new isolates and including sequences from type material for all availableAureobasidiumspecies. Data on growth, physiological profiles, micro- and macromorphological attributes were also collected and analysed. Several DNA-based species delimitation methods were evaluated for their ability to delimit species. We found that assimilation of D-quinic acid, L-sorbose, D-mannitol, gluconolactone, erythritol, L-arabinose, and sodium succinate dibasic hexahydrate were important in delineating species ofAureobasidiumand note that production of pigmentation in culture often takes longer than the 14 d standard for carbon assimilations. Genealogical concordance phylogenetic species recognition criteria (GCPSR) provided the most consistent results for species delimitation. We describe nine new species ofAureobasidium (A. albui,A. cavalettoi,A. diazvalderramae,A. ellingtonae,A. essambei,A. peruvianum,A. rubi,A. toomeae, andA. vanuatuense), make new combinations forA. aubasidani(≡ A. pullulansvar.aubasidani),A. fermentans(≡ Pullularia fermentans), andA. mahoniae(≡ Selenophoma mahoniae), validate and provide descriptions forA. mustiandA. uvarum, and provide lecto- and epitypes forDematium pullulans,the basionym ofA. pullulans. Finally, we resolved the phylogeny forAureobasidium, reduceKabatiella(based onK. microsticta) to synonymy, and provide an updated list of species to facilitate future studies. 

The subphylum Saccharomycotina is a lineage in the fungal phylum Ascomycota that exhibits levels of genomic diversity similar to those of plants and animals. The Saccharomycotina consist of more than 1 200 known species currently divided into 16 families, one order, and one class. Species in this subphylum are ecologically and metabolically diverse and include important opportunistic human pathogens, as well as species important in biotechnological applications. Many traits of biotechnological interest are found in closely related species and often restricted to single phylogenetic clades. However, the biotechnological potential of most yeast species remains unexplored. Although the subphylum Saccharomycotina has much higher rates of genome sequence evolution than its sister subphylum, Pezizomycotina , it contains only one class compared to the 16 classes in Pezizomycotina . The third subphylum of Ascomycota , the Taphrinomycotina , consists of six classes and has approximately 10 times fewer species than the Saccharomycotina . These data indicate that the current classification of all these yeasts into a single class and a single order is an underappreciation of their diversity. Our previous genome-scale phylogenetic analyses showed that the Saccharomycotina contains 12 major and robustly supported phylogenetic clades; seven of these are current families ( Lipomycetaceae , Trigonopsidaceae , Alloascoideaceae , Pichiaceae , Phaffomycetaceae , Saccharomycodaceae , and Saccharomycetaceae ), one comprises two current families ( Dipodascaceae and Trichomonascaceae ), one represents the genus Sporopachydermia , and three represent lineages that differ in their translation of the CUG codon (CUG-Ala, CUG-Ser1, and CUG-Ser2). Using these analyses in combination with relative evolutionary divergence and genome content analyses, we propose an updated classification for the Saccharomycotina , including seven classes and 12 orders that can be diagnosed by genome content. This updated classification is consistent with the high levels of genomic diversity within this subphylum and is necessary to make the higher rank classification of the Saccharomycotina more comparable to that of other fungi, as well as to communicate efficiently on lineages that are not yet formally named.